Light source device and projector

ABSTRACT

A light source lamp unit ( 10 ) includes a light source lamp ( 11 ), an ellipsoidal reflector ( 12 ) and a plate body ( 19 ). The plate body ( 19 ) is provided behind the reflector ( 12 ) with a gap kept therebetween, which has a shape corresponding to the profile of a reflecting portion ( 122 ) of the reflector ( 12 ). A cooling channel for passing a cooling air is formed between the plate body ( 19 ) and the reflector ( 12 ). The width of the cooling channel in a direction along an optical axis of the light source lamp ( 11 ) is minimized at a part near a neck portion ( 121 ) of the reflecting portion ( 122 ) and enlarged toward the peripheral edge of the reflecting portion ( 122 ) of the reflector ( 12 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light source device and a projector.

2. Description of Related Art

Conventionally, projectors that form an optical image by modulating alight beam irradiated by a light source in accordance with imageinformation and project the optical image in an enlarged manner are usedin the field of home theaters.

The projectors have a light source device having a light source lamp(light-emitting tube), a reflector that reflects a light beam irradiatedby the light source lamp and a lamp housing that houses the light sourcelamp and the reflector.

In recent projectors, in order to clearly display the projected opticalimage, it is required to increase the luminance of a light source lamp.Since the high-luminance light source lamp causes to raise thetemperature inside the lamp housing, the air in the projector isintroduced from the upper side of the lamp housing of the light sourcedevice to be flown to the lower side thereof to cool the inside of thelamp housing (For instance, see JP08-186784A, page 9, FIG. 7).

In the above cooling method, however, the cooling air flows only fromthe top to the bottom of the lamp housing, so that it is difficult toequally cool the reflector. Therefore, the reflector may be partlysubjected to high temperature. Ordinary, a reflecting film that reflectsvisible rays and transmits infrared rays and ultraviolet rays of thelight beam irradiated from the light source lamp is attached on thereflecting portion of the reflector, but the reflecting film may bepeeled off because of the partial high temperature of the reflector.

As disclosed in the above publication, since the reflector and the lightsource lamp are traditionally housed in the lamp housing, the infraredrays and the ultraviolet rays transmitted through the reflectorirradiate the wall of the lamp housing located behind the reflector. Thetemperature of the wall of the lamp housing then becomes high, thusbeing thermally deformed. Further, due to ultraviolet rays transmittedthrough the reflector, the lamp housing may be thermally and chemicallydecomposed, and accordingly, the wall surface of the lamp housing may bedeteriorated and whitened. Additionally, adhesion of siloxane generatedby chemical decomposition on optical components may deteriorate theperformance thereof, and foul smell caused by generation of endocrinedisrupters may lower the reliability.

Incidentally, the above disadvantages are occurred not only when theinfrared rays and the ultraviolet rays transmitted through the reflectorirradiate the wall of the lamp housing but also when they irradiate thewall of the light guide housing the optical components.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a light source deviceand a projector having the light source device, the light source devicebeing capable of efficiently cooling a reflector, preventingdeformation, deterioration and whitening of a lamp housing and a lightguide and inhibiting the generation of siloxane and endocrinedisrupters.

A light source device according to an aspect of the present invention,includes: a light-emitting tube including a light-emitting portion thatgenerates light by an electric discharge between electrodes and a firstand a second sealing portions provided on both sides of thelight-emitting portion; a reflector provided behind the light-emittingportion of the light-emitting tube and having a reflecting portion thatirradiates the light beam irradiated by the light-emitting tube afteraligning in a predetermined direction, in which the reflecting portionof the reflector reflects visible lights and transmits infrared rays andultraviolet rays in the light beam irradiated by the light-emittingportion of the light-emitting tube, a plate body is provided behind thereflector spaced apart from the reflecting portion of the reflector witha predetermined gap, the plate body having a shape corresponding to theprofile of the reflecting portion of the reflector and absorbing theinfrared rays and the ultraviolet rays transmitted through thereflecting portion, and a cooling channel that passes a cooling fluid isformed between the reflecting portion of the reflector and the platebody.

Note that, the plate body is only required to absorb the infrared raysand the ultraviolet rays, which may be coated with anodizedblack-aluminum on the surface thereof.

With such arrangement, since the plate body with a shape correspondingto the profile of the reflecting portion of the reflector is disposedbehind the reflector, and the cooling channel is formed between theplate body and the reflecting portion, the entire reflector can beequally and efficiently cooled. Accordingly, the reflection filmattached on the reflecting portion of the reflector can be preventedfrom peeling off due to the heat.

Further, since the plate body is disposed behind the reflector for thepurpose of absorbing the infrared rays and the ultraviolet raystransmitted through the plate body, the infrared rays and theultraviolet rays etc. do not irradiate the walls of the lamp housing orthe light guide located behind the reflector when the light-emittingportion, the reflector and the plate body are housed in the lamp housingor the light guide, thus preventing the wall from being thermallydeformed.

Note that, though the plate body generates heat due to the absorption ofthe infrared rays and the ultraviolet rays, the plate body can be cooledby the air passing through the cooling channel.

Since the ultraviolet rays etc. do not irradiate the walls of the lamphousing or the light guide located behind the reflector, the lamphousing or the light guide is not thermally or chemically decomposed,thus preventing the lamp housing or the light guide from beingdeteriorated and whitened. Because the lamp housing or the light guideis not chemically decomposed, generation of siloxane and endocrinedisrupters can be avoided. Accordingly, degradation of the performanceof the optical components due to adhesion of siloxane on the opticalcomponents, and a low reliability due to generation of foul smell alongwith generation of endocrine disrupters can be dissolved.

Furthermore, an exhaust fan is ordinarily provided in the exterior caseof the projector that houses a light source device etc. in order to coolthe light source device by introducing the air in the exterior case intothe light source device, and the air introduced by the exhaust fan isdischarged from an exhaust port formed on the exterior case. A pluralityof louvers conventionally attached to the exhaust port at closeintervals in order to inhibit the light leakage from the light sourcedevice. When the air is discharged from the exhaust port, since theconsiderable air resistance is generated against the louvers, therevolution number of the exhaust fan must be raised for efficientlycooling the light source device, thus not lowering the noise level.

In contrast, with the arrangement of the present invention, since theplate body having a shape corresponding to the profile of the reflectingportion is provided behind the reflector, the light beam emitted by thelight-emitting portion of the light-emitting tube is prevented fromleaking to the backside of the reflector. Therefore, the louversattached on the exhaust port of the exterior case are not required to bearranged at close intervals, thus reducing the air resistance of thelouvers. Accordingly, the revolution number of the exhaust fan can beset low, thus lowering the noise level.

Though it is conventionally required that a reflector and a,light-emitting tube are entirely covered by a lamp housing forpreventing the light emitted by the light-emitting tube from leaking tothe backside of the reflector, in the arrangement of the presentinvention, the light emitted by the light-emitting tube is preventedfrom leaking to the backside of the reflector by the plate body and thelamp housing need not to cover the backside of the reflector, thusdownsizing the lamp housing.

Further, since the plate body is provided behind the reflector, thebroken pieces of the light-emitting tube are prevented from scatteringto the backside of the reflector even when the light-emitting tube isexploded. Thus, the safety of the light source device can be enhanced.

In the above aspect of the present invention, the light source devicemay preferably include: a neck portion provided on the reflectingportion of the reflector to support the sealing portion of thelight-emitting portion, in which the width of the cooling channel formedbetween the reflecting portion of the reflector and the plate body alongan optical axis direction of the light-emitting portion may preferablybe minimized at a part near the neck portion of the reflecting portionand enlarged toward a peripheral edge of the reflector.

With this arrangement, the width of the cooling channel is enlargedtoward the peripheral edge of the reflector, thus promoting the coolingair to be introduced from or discharged toward the peripheral edge ofthe reflector.

In the above aspect of the present invention, the minimum width of thecooling channel may preferably be from 5 to 15 mm.

If the minimum width of the cooling channel is less than 5 mm, thecooling air is difficult to pass through the cooling channel and thereflector and the plate body may not be sufficiently cooled because thecooling channel is so narrow that great air passage resistance isdeveloped therein.

If the minimum dimension is more than 15 mm, the cooling efficiency maybe lowered since the cooling channel is so wide that turbulence islikely to be generated, thereby restricting the flow of the fluid alongthe reflector and the plate body.

With this arrangement, since the minimum width of the cooling channel isfrom 5 to 15 mm, the above disadvantages can be avoided, thusefficiently cooling the reflector and the plate body.

In the above aspect of the present invention, the surface of the platebody may preferably have irregularities on a side near the reflector.

The heat of the plate body generated by absorbing the ultraviolet raysand the infrared rays is cooled by the cooling fluid passing through thecooling channel. In this arrangement, since the surface of the platebody has irregularities on the side near the reflector, the heatradiation area of the plate body can be widely secured, thus efficientlyradiating the absorbed heat.

In the above aspect of the present invention, the surface emissivity ofthe surface of the plate body may preferably be 0.8 or above on a sidenear the reflector.

Since the surface emissivity of the plate body is 0.8 or above, the heatabsorbed by the plate body can be efficiently radiated.

In the above aspect of the present invention, the light source devicemay further includes a neck portion provided on the reflecting portionof the reflector to support the sealing portion of the light-emittingportion, in which the plate body may preferably be made of aheat-conductive material and fixed on the neck portion of the reflector.

With this arrangement, by attaching the plate body made of theheat-conductive material on the neck portion, the heat of the reflectorcan be transferred to the plate body to cool the reflector.

In the above aspect of the present invention, in the sealing portions ofthe light-emitting tube the one sealing portion provided on a side nearthe reflector may preferably be fixed on the reflector via a cylindricalheat-conductive member with one end of the heat-conductive memberextending behind the reflector, and the plate body may preferably bemade of a heat-conductive material and be abutted on an end thereof.

With this arrangement, since the cylindrical heat-conductive member isattached to the sealing portion of the light-emitting tube, thelight-emitting portion can be cooled by transferring the heat generatedby the light-emitting portion of the light-emitting tube to theheat-conductive member.

By abutting the plate body made of the heat-conductive material to theheat-conductive member, the heat transferred to the heat-conductivemember can be radiated via the plate body. Accordingly, thelight-emitting portion of the light-emitting tube can be efficientlycooled via the heat-conductive member and the plate body.

A projector according to another aspect of the present invention formsan optical image by modulating a light beam irradiated by a light sourcein accordance with image information and projects the optical image inan enlarged manner, the projector including the above-described lightsource device.

Since the projector has the light source including any one of featuresdescribed above, the same advantages as the above light source devicecan be obtained. In other words, advantages that the reflector can beefficiently cooled and the lamp housing or the light guide can beprevented from being thermally deformed can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration showing an optical system of aprojector according to an embodiment of the present invention;

FIG. 2 is a perspective view showing an outline of a light source deviceof the aforesaid embodiment;

FIG. 3 is a cross sectional view showing the structure of the lightsource device of the aforesaid embodiment;

FIG. 4 is an illustration showing the result of a simulation of anExample;

FIG. 5 is an illustration showing the result of a simulation of aComparison 1;

FIG. 6 is an illustration showing the result of a simulation of aComparison 2; and

FIG. 7 is an illustration showing the result of a simulation of aComparison 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

An embodiment of the present invention will be described below withreference to the attached drawings.

FIG. 1 is a schematic illustration showing an optical system of aprojector 1 according to an embodiment of the present invention. Theprojector 1 is an optical equipment that forms an optical image bymodulating a light beam irradiated by a light source in accordance withimage information and projects the optical image on a screen in anenlarged manner, the projector 1 including a light source lamp unit 10(light source device), a uniform illumination optical system 20, acolor-separating optical system 30, a relay optical system 35, anoptical device 40 and a projection optical system 50. Optical elementsof the optical systems 20 through 35 are housed with the positionsthereof being adjusted within a light guide 2 where a predeterminedillumination optical axis P is set. Though not shown, the light guide 2includes a box-shaped lower light guide opened at the upper face thereofand a lid-shaped upper light guide closing the opening of the lowerlight guide.

The light source lamp unit 10 emits the light beam irradiated by thelight source lamp 11 after aligning in a predetermined direction toilluminate the light source device 40, and includes a light source lamp(light-emitting tube) 11, an ellipsoidal reflector 12 and a collimatingconcave lens 14, of which details will be described below.

The light beam irradiated by the light source lamp 11 is emitted as aconvergent light after the irradiating direction thereof being alignedtoward the front side of the optical device by the ellipsoidal reflector12, which is collimated by the collimating concave lens 14 to beirradiated to the uniform illumination optical system 20.

The uniform illumination optical system 20 is an optical system forseparating the light beam irradiated by the light source lamp unit 10into a plurality of sub-beams to equalize the in-plane illuminance of anilluminating area, the uniform illumination optical system 20 includinga first lens array 21, a second lens array 22, a polarization converter23, a superposing lens 24 and a reflection mirror 25.

The first lens array 21 functions as a light beam separating opticalelement that separates the light beam irradiated by the light sourcelamp 11 into a plurality of sub-beams, which has a plurality of smalllenses arranged in a matrix on a plane orthogonal to the illuminationoptical axis P, each profile of the respective small lenses beingarranged to be approximately similar to the profile of image formationareas of liquid crystal panels 42R, 42G, 42B of the optical device 40(described below).

The second lens array 22 is an optical element for condensing theplurality of sub-beams separated by the above first lens array 21, whichhas small lenses arranged in a matrix on a plane orthogonal to theillumination optical axis P as the first lens array 21, however, eachprofile of the respective small lenses is not required to correspondwith the profile of the image formation areas of the liquid crystalpanels 42R, 42G, 42B since the second lens array 22 is for condensingthe light.

The polarization converter 23 aligns a polarizing direction of therespective sub-beams separated by the first lens array 21 into a linearpolarized light of a predetermined direction.

Though not shown, the polarization converter 23 has an alternatearrangement of a polarization separating film and a reflection mirrorboth inclined relative to the illumination optical axis P. Thepolarization separating film transmits either P-polarized light beam orS-polarized light beam contained in the respective sub-beams whereasreflects the other polarized light beam. The reflected polarized lightbeam is bent by the reflection mirror to be irradiated in a direction towhich the transmitted polarized light beam is irradiated, i.e., in adirection along the illumination optical axis P. One of the irradiatedP-polarized light beam and the S-polarized light beam is converted by aretardation plate provided on a light irradiation side of thepolarization converter 23 so that the direction of all polarized lightbeam is aligned. With the use of such polarization converter 23, thelight beam irradiated by the light source lamp 11 can be aligned as thepolarized light beam in a predetermined direction, so that theutilization ratio of the source light to be used in the optical device40 can be enhanced.

The superposing lens 24 is an optical element that condenses theplurality of sub-beams after passing the first lens array 21, the secondlens array 22 and the polarization converter 23 to superpose thecondensed light beam on the image formation areas of the liquid crystalpanels 42R, 42G, 42B. Though the superposing lens 24 is a spherical lensin the present embodiment, a light transmitting area there of having aflat light incident side of and a spherical light irradiation side, anaspherical lens may alternatively be used.

The light beam irradiated by the superposing lens 24 is bent by thereflection mirror 25 and irradiated to the color-separating opticalsystem 30.

The color-separating optical system 30 has two dichroic mirrors 31 and32 and a reflection mirror 33, the dichroic mirrors 31 and 32 separatingthe plurality of sub-beams irradiated by the uniform illuminationoptical system 20 into three color lights of red (R), green (G) and blue(B).

The dichroic mirrors 31 and 32 are optical elements each having a baseon which a wavelength-selection film that reflects a light beam of apredetermined wavelength and transmits a light beam of the otherwavelength is formed, in which the dichroic mirror 31 disposed on theupstream of the optical path is a mirror that transmits the red lightand reflects other color lights. The dichroic mirror 32 disposed on thedownstream of the optical path is a mirror that reflects the green lightand transmits the blue light.

The relay optical system 35 has an incident-side lens 36, a relay lens38, and reflection mirrors 37 and 39, which guides the blue lighttransmitted through the dichroic mirror 32 of the color-separatingoptical system 30 to the optical device 40. Incidentally, the relayoptical system 35 is used for the optical path of the blue light inorder to avoid deterioration in the light utilization efficiency onaccount of light dispersion and the like caused by the longer length ofthe optical path of the blue light than the optical path of other colorlights. Though such arrangement is used in the present embodimentbecause of the longer optical path of the blue light, the optical pathof the red light may alternatively be lengthened.

The red light separated by the above-described dichroic mirror 31 isbent by the reflection mirror 33 and, subsequently, fed to the opticaldevice 40 through a field lenses 41. The green light separated by thedichroic mirror 32 is directly fed to the optical device 40 through thefield lenses 41. The blue light is condensed and bent by the lenses 36,38 and the reflection mirrors 37 and 39 of the relay optical system 35to be fed to the optical device 40 through the field lenses 41.Incidentally, the field lenses 41 provided on the upstream of theoptical path of the respective color lights of the optical device 40 areprovided for converting the respective sub-beams irradiated by thesecond lens array 22 into light beams parallel to the illuminationoptical axis.

The optical device 40 forms a color image by modulating the incidentlight beam in accordance with image information, the optical device 40including liquid crystal panels 42 (optical modulator) to be illuminatedand a cross dichroic prism 43 (color-combining optical system). Inaddition, incident-side polarization plates 44 are respectivelyinterposed between the field lenses 41 and the liquid crystal panels42R, 42G, 42B, and though not shown, irradiation-side polarizationplates are respectively interposed between the liquid crystal panels42R, 42G, 42B and the cross dichroic prisms 43 so as to modulate therespective incident color lights through the incident-side polarizationplates 44, the liquid crystal panels 42R, 42G, 42B and theirradiation-side polarization plates.

The liquid crystal panels 42R, 42G, 42B each have a pair of transparentglass substrates with liquid crystal as electrooptic material sealedtherebetween to modulate the polarizing direction of the polarized lightbeam irradiated by each incident-side polarization plate 44 inaccordance with given image signal by using, for instance, apolycrystalline silicon TFT as a switching element. Each image formationarea of the liquid crystal panels 42R, 42G, 42B for modulation has arectangular shape having diagonal length of 0.7 inch.

The cross dichroic prism 43 is an optical element that combines theoptical image irradiated by the irradiation-side polarization plates andmodulated for each color light to form a color image. The cross dichroicprism 43 contains four right-angle prisms mutually bonded in anapproximately planarly-viewed square. Dielectric multi-layer films areformed on the boundaries where the four right-angle prisms are mutuallybonded. One of the X-shaped dielectric multi-layer films reflects thered light and the other one reflects the blue light, the red light andthe blue light being bent by the dielectric multi-layer films andaligned with the advancement direction of the green light, so that thethree color lights are combined.

The color image irradiated by the cross dichroic prism 43 is projectedby the projection optical system 50 in an enlarged manner to form alarge-size image on a screen (not shown).

The above-described light source lamp unit 10 (light source device) isattachable to and detachable from the light guide 2 so as to be replacedwhen the light source lamp 11 being exploded or the luminance thereofbeing deteriorated due to its life-span.

More specifically, as shown in FIGS. 2 and 3, the light source lamp unit10 includes a lamp housing 15, a cover portion 16, a heat-conductivemember 17, a heat-radiation fin 18 and a plate body 19 along with theabove-described light source lamp 11, the ellipsoidal reflector 12 andthe collimating concave lens 14.

The light source lamp 11 as a light-emitting tube has a silica glasstube with the central portion thereof being spherically bulged, thecentral portion being a light-emitting portion 111 and the portionsextending on both sides of the light-emitting portion 111 being sealingportions 112. In the embodiment, one of the sealing portions 112 on theside near the ellipsoidal reflector 12 is a first sealing portion 112Awhereas the other one is a second sealing portion 112B.

Though not shown in FIG. 3, a pair of tungsten electrodes spaced apartwith each other, mercury, rare gas and a small amount of halogen aresealed in the light-emitting portion 111.

The sealing portions 112 are sealed by glass material etc. with metalfoil of molybdenum being inserted therein, the metal foil beingelectrically connected with the electrodes in the light-emitting portion111. The metal foil is connected to a lead wire 113 as an electrodeoutgoing line, the lead wire 113 extending to the outside of the lightsource lamp 11.

When a predetermined voltage is applied on the lead wire 113, electricdischarge is generated between the pair of electrodes and thelight-emitting portion 111 emits light.

The ellipsoidal reflector 12 is an integral glass molding including anellipsoidal curved reflecting portion 122 that irradiates the light beamirradiated by the light source lamp 11 after aligning the light beam ina predetermined direction and a neck portion 121 provided on thereflecting portion 122 for the first sealing portion 112A of the lightsource lamp 11 to be inserted.

An insertion hole 123 is formed on the neck portion 121 at the center,and the first sealing portion 112A is disposed at the center of theinsertion hole 123. Note that, the first sealing portion 112A issupported by and fixed on the neck portion 121 via the below-describedheat-conductive member 17.

The reflecting portion 122 is formed by vacuum evaporation of a metalthin film on the ellipsoidal curved glass surface, and though not shown,a reflection film (cold mirror) that reflects visible lights andtransmits infrared rays is attached on the reflection surface of thereflecting portion 122.

The above light source lamp 11 is arranged inside the reflecting portion122 so that the light-emission center between the pair of electrodes inthe light-emitting portion 111 is coincident with the first focalposition of the ellipsoidal curve of the reflecting portion 122.

Once the light source lamp 11 is lit, the light beam emitted by thelight-emitting portion 111 is reflected by the reflection surface of thereflecting portion 122 to be a convergent light converged on the secondfocal position of the ellipsoidal curve.

When the light source lamp 11 is fixed on such ellipsoidal reflector 12,the first sealing portion 112A on which the below-describedheat-conductive member 17 is attached is inserted into the insertionhole 123 of the ellipsoidal reflector 12 and positioned so that thelight-emission center between the pair of electrodes in thelight-emitting portion 111 is coincident with the focal position of theellipsoidal curve of the reflecting portion 122 and a silica-aluminainorganic adhesive is filled inside the insertion hole 123. In theembodiment, the lead wire 113 outgoing from the second sealing portion112B is also exposed to the outside through the insertion hole 123.

The dimension of the reflecting portion 122 in the optical axisdirection is shorter than the length of the light source lamp 11, sothat when the light source lamp 11 is fixed on the ellipsoidal reflector12, the second sealing portion 112B of the light source lamp 11 projectsfrom a light incident opening of the ellipsoidal reflector 12, because

The heat-conductive member 17 is a cylindrical component attached on theoutside of the first sealing portion 112A of the light source lamp 11,the heat-conductive member 17 being inserted through the neck portion121 of the ellipsoidal reflector 12 together with the first sealingportion 112A to be fixed.

The heat-conductive member 17 and the first sealing portion 112A areadhered by an inorganic adhesive (not shown) having high thermalconductivity such as a silica-alumina or aluminum nitride adhesive.Though not shown, a slit is cut on the heat-conductive member 17 alongits longitudinal direction, the slit allowing thermal expansion of thefirst sealing portion 112A.

Any material may be used for the heat-conductive member 17 as long asthe material has higher thermal conductivity than the thermalconductivity of the light source lamp 11, which may preferably be amaterial with thermal conductivity of 5 W/(m·K) or higher such assapphire, quartz crystal, fluorite, alumina and aluminum nitride.

A first end of the heat-conductive member 17 extends from the neckportion 121 of the reflector 12 to the backside of the reflector 12 tobe exposed from the reflector 12. On the other hand, a second endextends to the part near the light-emitting portion 111 of the lightsource lamp 11.

The heat-radiation fin 18 is integrally formed with the heat-conducivemember 17 at the first end.

The heat-radiation fin 18 has an approximately planarly-viewed C-shapecomposed of mutually opposing planarly-viewed rectangular first walls181 and a planarly-viewed rectangular second wall 182 that connectsproximal ends of the first walls 181, which is disposed so that anopening formed at the side opposing to the second wall 182 faces thereflector 12. Three pieces 183 extending from the second wall 182 towardthe opening are disposed between the first walls 181 approximately inparallel to the first walls 181.

In the embodiment, though the heat-radiation fin 18 is provided on theheat-conductive member 17, the heat-radiation fin may not be provided.

The plate body 19 is disposed behind the reflector 12 (a side oppositeto the light reflection side) spaced apart from the reflector 12 andformed in a shape corresponding to the profile of the reflecting portion122 of the reflector 12, for instance, in a truncated pyramid.Specifically, the plate body 19 of the embodiment has a through hole191A, into which the heat conductive member 17 is inserted through, theplate body 19 including a planarly-viewed rectangular first side 191being approximately orthogonal to the longitudinal direction of thelight source lamp 11 and four second sides 192 extending from therespective edges of the first side 191 to the side of the opening of thereflector 12.

In this embodiment, though the plate body is formed in a truncatedpyramid, the plate body may be formed in a six-sided truncated pyramid,or in an ellipsoidal curved shape approximately the same as thereflecting portion 122 of the reflector 12.

When the heat-conductive member 17 is inserted through the through hole191A of the first side 191, the plate body 19 is abutted on theheat-conductive member 17.

One of four second sides 192 located on the upper side of the reflector12 is integrally formed with a fixing piece 193 for fixing the platebody 19 on a vertical portion 152 (described below) of the lamp housing15. A through hole 193A is formed on the fixing portion 193 so that theplate body 19 is fixed on the lamp housing 15 by inserting a projection155 of the vertical portion 152 through the through hole 193A.

A cooling channel for passing the cooling air is provided between theplate body 19 and the reflector 12. The width of the cooling channel ina direction along the optical axis of the light source lamp 11 isminimized around the neck portion 121 of the reflecting portion 122 andenlarged toward the peripheral edge of the reflecting portion 122 of thereflector 12. In other words, the dimension (T1 in FIG. 3) between thefirst side 191 and a part near the neck portion 121 of the reflectingportion 122 is the smallest whereas the dimension (T2 in FIG. 3) betweenthe peripheral edge of the second sides 192 and the peripheral edge ofthe reflecting portion 122 is the largest. The dimension (T1 in FIG. 3)between the first side 191 and the part near the neck portion 121 of thereflecting portion 122 is from 5 to 15 mm, preferably around 10 mm.

The plate body 19 absorbs ultraviolet rays and infrared rays and is madeof a heat-conductive material such as an aluminum alloy, which surfaceis coated with anodized black-aluminum. Further, the surface of thefirst side 191 and the second sides 192 have irregularities on the sidenear the reflector 12, to have 0.8 surface emissivity.

As shown in FIG. 3, the lamp housing 15 is an integral synthetic resinmolding with an L-shaped cross section, the lamp housing 15 having ahorizontal portion 151 and the vertical portion 152.

The horizontal portion 151 engages with the wall of the light guide 2 toconceal the light source lamp unit 10 within the light guide 2 toprevent light leakage. Though not shown, the horizontal portion 151 hasa terminal block for electrically connecting the light source lamp 11 toan external power source, the terminal block being connected to the leadwire 113 of the light source lamp 11.

The vertical portion 152 is a part for positioning the ellipsoidalreflector 12 in the optical axis direction, in the embodiment, thedistal end of the ellipsoidal reflector 12 at the side of the lightirradiation opening being fixed to the vertical portion 152 by anadhesive. An opening 153 that transmits the light beam irradiated by theellipsoidal reflector 12 is formed on the vertical portion 152.

Further, projections 154 are provided on the horizontal portion 151 andthe vertical portion 153. The projections 154 respectively engage withrecesses inside the light guide 2 so that the light-emission center ofthe light source lamp 11 is located on the illumination optical axis P.

Further, a projection 155 is formed on the vertical portion 152 at theupper side for inserting through the through hole 193A of the fixingpiece 193 of the plate body 19.

The cover portion 16 is an integral metal molding having a heat absorber161 formed in an approximately conical cylinder attached to the opening153 of the vertical portion 152 of the lamp housing 15, a plurality ofheat-radiation fins 162 projected outside the heat absorber 161 and alens attachment 163 formed on a distal end of the heat absorber 161.

The heat absorber 161 absorbs radiant heat of the light source lamp 11and convection heat in the sealed area surrounded by the ellipsoidalreflector 12 and the cover portion 16, the inside of the heat absorber161 being coated with anodized black-aluminum. The approximately conicalslant surface of the heat absorber 161 is parallel to the inclination ofthe convergent light of the ellipsoidal reflector 12 to inhibit thelight beam irradiated by the ellipsoidal reflector 12 from beingirradiated on the interior surface of the heat absorber 161.

The plurality of the heat-radiation fins 162 are plate bodies extendingin the direction orthogonal to the optical axis of the light source lampunit 10, where gaps for sufficiently passing the cooling air are formedbetween the heat-radiation fins 162.

The lens attachment 163 is defined by a cylindrical part protruded onthe distal end of the heat absorber 161 and the collimating concave lens14 for collimating the convergent light of the ellipsoidal reflector 12is attached to the cylindrical part. Though not shown, the collimatingconcave lens 14 is fixed to the lens attachment 163 by an adhesive. Whenthe collimating concave lens 14 is attached to the lens attachment 163,the area inside the light source lamp unit 10 is completely sealed, sothat the broken pieces of the light source lamp 11 are not scattered tothe outside if being exploded even when the light source lamp 11 isexploded.

The above-described light source lamp unit 10 is housed in the lightguide 2 of the projector 1.

Though not shown in FIG. 1, the projector 1 includes an exhaust fanarranged adjacent to the light source lamp unit 10, in which the exhaustfan draws in the cooling air inside the projector 1, blows the coolingair along the extending direction of the heat-radiation fin 162 of thecover portion 16, passes the cooling air through the cooling channelformed between the plate body 19 and the reflector 12 and further blowsthe cooling air to the heat-conductive member 17 and the heat-radiationfin 18. Additionally, an exhaust port for discharging the air from theexhaust fan is provided on an exterior case (not shown) of the projector1, a light shielding louvers being attached on the exhaust port.

Next, cooling process of the light source lamp unit 10 according to theprojector 1 will be described.

When the projector 1 is powered so the light source lamp 11 is lit, awhite light is irradiated. At this time, the exhaust fan inside theprojector 1 is driven.

The heat generated by the light-emitting portion 111 of the light sourcelamp 11 is transferred to the heat-conductive member 17 via the firstsealing portion 112A. Heat is exchanged between a part of the heattransferred to the heat-conductive member 17 and the cooling air in theexterior case drawn in by the exhaust fan to cool the heat-conductivemember 17.

Another part of the heat transferred to the heat-conductive member 17 istransferred to the heat-radiation fin 18, and heat is exchanged betweenthe heat-radiation fin 18 and the cooling air so that the heat isradiated from the heat-radiation fin 18.

Still another part of the heat transferred to the heat-conductive member17 is transferred to the plate body 19 fixed on the heat-conductivemember 17, and heat is exchanged between the plate body 19 and the airpassing through the cooling channel formed between the plate body 19 andthe reflector 12.

The heat is also generated on the reflector 12 that reflects the lightbeam emitted by the light-emitting portion 111. The heat of thereflector 12 is exchanged into the cooling air passing through thecooling channel formed between the reflector 12 and the plate body 19 soas to cool the reflector 12.

Further, the light source lamp unit 10 generates heat due to theabsorption of the infrared rays and the ultraviolet rays irradiated bythe light-emitting portion 111. A method of cooling the heat will bedescribed below.

The infrared rays and the ultraviolet rays radiated from thelight-emitting portion 111 to the backside thereof are transmittedthrough the reflector 12 and absorbed by the plate body 19 to generatethe heat at the plate body 19. The heat is exchanged into the coolingair passing through the cooling channel formed between the plate body 19and the reflector 12 to cool the plate body 19.

Incidentally, approximately 30% of the ultraviolet rays and the infraredrays irradiated by the light-emitting portion 111 transmit through thereflector 12.

On the other hand, the infrared rays and the ultraviolet rays radiatedforward the light-emitting portion 111 are absorbed by the heat absorber161 of the cover portion 16. The air heated by radiant heat of the lightsource lamp 11 causes convection inside, and heat is exchanged betweenthe heated air and the inner circumference of the heat absorber 161 ofthe cover portion 16, thereby absorbing the heat to be cooled. The heatabsorbed by the heat absorber 161 is transferred to the heat-radiationfin 162, and heat exchange is occurred with the cooling blast from thecooling fan to cool the heat-radiation fin.

According to the present embodiment, following advantages can beobtained.

-   (1) Since the plate body 19 having a shape corresponding to the    profile of the reflecting portion 122 of the reflector 12 is    disposed behind the reflector 12 and the cooling channel is formed    between the plate body 19 and the reflecting portion 122, the entire    reflector 12 can be equally and efficiently cooled. Since the    reflector 12 can be equally cooled, the reflection film attached on    the reflecting portion 122 of the reflector 12 is not peeled off on    account of heat.-   (2) Since the plate body 19 disposed behind the reflector 12 serves    to absorb the infrared rays and the ultraviolet rays transmitted    through the reflecting portion 122 of the reflector 12, the infrared    rays and the ultraviolet rays do not irradiate the wall of the light    guide 2 located behind the reflector 12 even when the light source    lamp unit 10 is housed in the light guide 2. Therefore, the wall of    the light guide 2 can be prevented from being thermally deformed.

Note that, though heat is generated at the plate body 19 due toabsorption of the ultraviolet rays and the infrared rays, the plate body19 can be cooled by the air passing thorough the cooling channel.

-   (3) Since the ultraviolet rays etc. do not irradiate the wall of the    light guide 2 located behind the reflector 12, the light guide 2 is    not thermally nor chemically decomposed, thus preventing the light    guide 2 from being deteriorated or whitened. Because the light guide    2 is not chemically decomposed, generation of siloxane or endocrine    disrupters can be avoided. Accordingly, deterioration of the    performance of the optical components due to adhesion of siloxane on    the optical components, and low reliability due to generation of    foul smell in accordance with generation of endocrine disrupters can    be dissolved.-   (4) Since the plate body 19 formed in a shape corresponding to the    profile of the reflecting portion 122 is provided behind the    reflector 12, the light beam emitted by the light-emitting portion    111 of the light source lamp 11 can be prevented from leaking to the    backside of the reflector 12. Therefore, the louvers are not    required to be thickly arranged on the exhaust port of the exterior    case for inhibiting the light leakage, thus reducing the air    resistance of the louvers and facilitating the discharge of the air    sent from the exhaust fan. Accordingly, the revolution number of the    exhaust fan for cooling the light source lamp 11 can be set low,    thus lowering the noise level.-   (5) Conventionally, in order to prevent the light of the light    source lamp 11 from leaking to the backside or the front side of the    reflector 12, a lamp housing needs to entirely cover the reflector    12 and the light source lamp 11. On the other hand, in this    embodiment, since the plate body 19 is provided behind the reflector    12 and the cover portion 16 is provided at the front side of the    reflector 12, the light leakage from the light source lamp 11 can be    prevented. Accordingly, the lamp housing 15 need not to be formed to    entirely cover the reflector 12 and the light source lamp 11, thus    reducing the size of the lamp housing 15.-   (6) Further, the cover portion 16 is provided on the front side of    the reflector 12 and the plate body 19 is provided behind the    reflector 12, thereby preventing the broken pieces of the light    source lamp 11 from scattering to the front side and the backside of    the reflector 11 even when the light source lamp 12 is exploded.    Therefore, the safety of the light source lamp unit 10 can be    enhanced.

Particularly, since the cover portion 16 provided on the front of thereflector 12 has a completely sealed anti-explosion structure with thesafety can be further improved. Specifically, since the cover portion 16is made of a metal having excellent heat-conductivity so that radiantheat generated by the light source lamp 11 can be absorbed by the heatabsorber 161 and radiated from the heat-radiation fin 162, a vent holeetc. for cooling the inside of the cover portion 16 is not necessary,thus allowing the cover portion 16 to be completely sealed.

-   (7) The width of the cooling channel formed between the reflector 12    and the plate body 19 is enlarged toward the peripheral edge of the    reflector 12, thus promoting the cooling air to be introduced from    or discharged to the peripheral edge side of the reflector 12. In    other words, the exhaust fan provided adjacent to the reflector 12    allows sufficient air to pass through the cooling channel to be    discharged via the exhaust fan, thus efficiently cooling the    reflector 12 and the plate body 19.-   (8) If the minimum width of the cooling channel is less than 5 mm,    the cooling air is difficult to be passed through the cooling    channel and unavailable to sufficiently cool the reflector and the    plate body because the cooling channel is so narrow that the air    resistance is caused in the passage. If the minimum width is more    than 15 mm, the cooling air is difficult to flow along the reflector    and the plate body so that the cooling efficiency may be lowered due    to because the cooling channel is so wide that the turbulent flow is    likely caused. In contrast, in the embodiment, since the width of    the cooling channel is from 5 to 15 mm, sufficient cooling air can    pass through the cooling channel and the turbulent flow can be    prevented, so that the reflector 12 and the plate body 19 can be    sufficiently cooled.-   (9) In this embodiment, since the surface of the plate body 19 has    irregularities on the side near the reflector 12, the heat radiation    area of the plate body 19 can be widely secured, thus efficiently    radiating the absorbed heat. Further, since the surface emissivity    of the surface of the plate body 19 is 0.8 or above, the heat    generated on the plate body 19 by absorbing the ultraviolet rays and    the infrared rays can be efficiently radiated, and the heat can be    efficiently exchanged with the air passing through the cooling    channel.-   (10) Since the cylindrical heat-conductive member 17 is attached to    the sealing portion 112A of the light source lamp 11, the heat of    the light-emitting portion 111 of the light source lamp 11 is    transferred from the sealing portion 112A to the heat-conductive    member 17, thus cooling the light-emitting portion 111.

By abutting the heat-conductive plate body 19 to the heat-conductivemember 17, the heat transferred to the heat-conductive member 17 can beradiated via the plate body 19. Therefore, the light-emitting portion111 of the light source lamp 11 can be efficiently cooled via theheat-conductive member 17 and the plate body 19.

Incidentally, the scope of the present invention is not restricted tothe above-described embodiment, but includes modifications andimprovements as long as an object of the present invention can beachieved.

For example, in the above embodiment, though the heat-conductive member17 is attached to the first sealing portion 112A of the light sourcelamp 11, the heat-conductive member 17 may not be provided. Accordingly,the number of the components can be reduced. In such case, the platebody 19 may be fixed on the neck portion 121 of the reflector 12. Withthis arrangement, the heat of the reflector 12 can be transferred toand. radiated from the plate body 19.

In the above embodiment, though the surface emissivity on the side nearthe reflector 12 of the plate body 19 is 0.8 or above, the surfaceemissivity may be below 0.8. Further, though the surface of the platebody 19 has irregularities on the side near the reflector 12,irregularities may not be provided. Accordingly, the manufacturingprocess of the plate body can be facilitated.

Additionally, though the minimum width of the cooling channel is from 5to 15 mm in the above embodiment, the minimum width is not limitedthereto and may be less than 5 mm or more than 15 mm. In the aboveembodiment, though the width of the cooling channel is enlarged towardthe peripheral edge of the reflector 12, the cooling channel may have auniform width.

Further, a sub-reflection mirror, i.e. a reflection member that coverssubstantially half of the front side (in the light irradiationdirection) of the light-emitting portion 111 of the light source lamp 11may be provided on the light-emitting portion 111 of the light sourcelamp 11.

By attaching the sub-reflection mirror to the light-emitting portion111, the light emitted to the front side of the light-emitting portion111 is reflected by the sub-reflection mirror toward the ellipsoidalreflector 12 to be irradiated from the reflecting portion 122 of theellipsoidal reflector 12.

With the use of the sub-reflection mirror, since the light beam emittedto the front side of the light-emitting portion 111 is reflected to thebackside thereof, all of the light beams irradiated by the lightemitting portion 111 can be irradiated after being aligned in apredetermined direction even when the reflecting portion 122 has a smallellipsoidal curved surface, thus reducing the dimension of theellipsoidal reflector 12 in an optical axis direction.

Furthermore, in the above embodiment, though the cover portion 16 isattached on the reflector 12 on the side of the opening, the coverportion 16 may not be provided. In such case, a light guide may coverthe front of the reflector 12 to inhibit the light leakage from thelight source lamp 11.

In the above embodiment, though the lamp housing 15 has a L-shaped crosssection, the lamp housing 15 may be box-shaped. When the lamp housing 15is box-shaped, since the plate body 19 is provided behind the reflector12, the ultraviolet rays and the infrared rays do not irradiate the wallof the lamp housing, thus preventing the lamp housing from beingthermally deformed and thermally and chemically decomposed.

In the above embodiment, though the light source lamp unit 10 is appliedto the projector 1 having the liquid crystal panels 42R, 42G, 42B, thelight source lamp unit may be applied to a projector having an opticalmodulator with a micro mirror.

EXAMPLES

The present invention will be more specifically described below with anExample and Comparisons.

Example

A plate body 19A corresponding to the profile of the reflector 12 wasprovided behind the reflector 12, and the light source lamp 11, thereflector 12 and the plate body 19A were housed in a box-shaped lamphousing 15A. Then, an exhaust fan 7 for drawing and discharging the airin the lamp housing 15A was provided on a side of the lamp housing 15A.The light source lamp 11 was then lit and the exhaust fan 7 was rotatedto simulate the operation for observing temperature distribution.

Note that, the plate body 19A had an ellipsoidal curved shapecorresponding to the profile of the reflector 12 and the dimension ofthe gap defined between the reflector 12 and the plate body 19A wasapproximately 9 mm.

The result is shown in FIG. 4.

Comparison 1

A plate body was not provided behind the reflector 12. Other conditionswere the same as the Example.

The result of the simulation is shown in FIG. 5.

Comparison 2

A plate body 19B was provided behind the reflector 12. The plate body19B was not along the profile of the reflector 12, but extended straightwith being orthogonal to the optical axis of the light source lamp 11.The plate body 19B abutted on a part near the neck portion (not shown)of the reflecting portion 122 of the reflector 12. Other conditions werethe same as the Example.

The result of the simulation is shown in FIG. 6.

Comparison 3

The plate body 19B was provided behind the reflector 12 in the samemanner as the Comparison 2. The gap defined between the plate body 19Band the part near the neck portion (not shown) of the reflecting portion122 of the reflector 12 was approximately 3.5 mm. Other conditions werethe same as the Comparison example 2.

The result of the simulation is shown in FIG. 7.

Incidentally, referring to FIGS. 4 to 7, the temperature, of an area Ais approximately 180 to 140° C., that of an area B is approximately 139to 90° C., that of an area C is approximately 89 to 50° C. and that ofan area D is approximately 49 to 20° C.

(Comparison between Example and Comparisons 1 to 3)

In the Example, because the plate body 19A was provided, it was observedthat the temperature of the wall behind the reflector 12 of the lamphousing 15A was not raised. Additionally, since the plate body 19Ahaving a shape corresponding to the profile of the reflector 12 wasprovided, the reflector 12 could be efficiently cooled and it isobserved that the temperature of the reflector 12 was approximately 139to 90° C.

In the Comparison 1, since a plate body was not provided, thetemperature of the wall behind the reflector 12 was raised.

Since the plate body 19B was provided in the Comparisons 2 and 3, thetemperature of the wall arranged behind the reflector 12 of the lamphousing 15A was not raised. However, since the shape of the plate body19B was not corresponded to the profile of the reflector 12, thereflector 12 was not efficiently cooled and the temperature of thereflector 12 was high (approximately 180 to 140° C.).

Though not specifically showing in FIGS. 6 and 7, when the gap isprovided between the plate body 19B and the reflector 12 as in FIG. 7(Comparison 3), the temperature of the reflector 12 was slightly lowerthan an arrangement where no gap is provided as in FIG. 6 (Comparison2).

As described above, the effects of the present invention that thereflector can be efficiently cooled and the thermal deformation of thelamp housing and the light guide can be prevented could be confirmed.

1. A light source device, comprising: a light-emitting tube including alight-emitting portion that generates light by an electric dischargebetween electrodes and sealing portions provided on both sides of thelight-emitting portion; and a reflector provided behind thelight-emitting portion of the light-emitting tube and having areflecting portion that irradiates the light beam irradiated by thelight-emitting tube after aligning in a predetermined direction, whereinthe reflecting portion of the reflector reflects visible lights andtransmits infrared rays and ultraviolet rays in the light beamirradiated by the light-emitting portion of the light-emitting tube, areflecting portion of the reflector reflects visible lights andtransmits infrared rays in the light irradiated by the light-emittingportion of the light-emitting tube attached on the reflecting portion,wherein a plate body is provided behind the reflector spaced apart fromthe reflecting portion of the reflector with a predetermined gap, theplate body having a shape corresponding to the a profile of thereflection reflecting portion of the reflector and absorbing theinfrared rays and the ultraviolet rays transmitted through thereflecting portion, and wherein a cooling channel that passes a coolingfluid is formed between the reflecting portion of the reflector and theplate body, and wherein the surface emissivity of the surface of theplate body is 0.8 or above on a side near the reflector.
 2. The lightsource device according to claim 1, further comprising: a neck portionprovided on the reflecting portion of the reflector to support thesealing portions of the light-emitting portion, wherein the width of thecooling channel formed between the reflecting portion of the reflectorand the plate body along an optical axis direction of the light-emittingportion is minimized at a part near the neck portion of the reflectingportion and enlarged toward a peripheral edge of the reflector.
 3. Thelight source device according to claim 2, wherein the minimum width ofthe cooling channel is from 5 to 15 mm.
 4. The light source deviceaccording to claim 1, wherein the surface of the plate body hasirregularities on a side near the reflector.
 5. The light source deviceaccording to claim 1, further comprising: a neck portion provided on thereflecting portion of the reflector to support the sealing portions ofthe light-emitting portion, wherein the plate body is made of aheat-conductive material and fixed on the neck portion of the reflector.6. The light source device according to claim 1, wherein in the sealingportions of the light-emitting tube, the one sealing portion provided onthe side near the reflector is fixed on the reflector via a cylindricalheat-conductive member with one end extending behind the reflector, andwherein the plate body is made of a heat-conductive material and isabutted on an end of the heat-conductive member.
 7. A projector thatforms an optical image by modulating a light beam irradiated by a lightsource in accordance with image information and projects the opticalimage in an enlarged manner, the projector comprising: the light sourcedevice according to claim
 1. 8. The projector according to claim 7,further comprising: a neck portion provided on the reflecting portion ofthe reflector to support the sealing portions of the light-emittingportion, wherein the width of the cooling channel formed between thereflecting portion of the reflector and the plate body along an opticalaxis direction of the light-emitting portion is minimized at a part nearthe neck portion of the reflecting portion and enlarged toward aperipheral edge of the reflector.
 9. The projector according to claim 8,wherein the minimum width of the cooling channel is from 5 to 15 mm. 10.The projector according to claim 7, wherein the surface of the platebody has irregularities on a side near the reflector.
 11. The projectoraccording to claim 7, further comprising: a neck portion provided on thereflecting portion of the reflector to support the sealing portions ofthe light-emitting portion, wherein the plate body is made of aheat-conductive material and fixed on the neck portion of the reflector.12. The projector according to claim 7, wherein in the sealing portionsof the light-emitting tube, the one sealing portion provided on the sidenear the reflector is fixed on the reflector via a cylindricalheat-conductive member with one end extending behind the reflector, andwherein the plate body is made of a heat-conductive material and isabutted on an end of the heat-conductive member.
 13. A light sourcedevice, comprising: a light-emitting tube including a light-emittingportion that generates light by an electric discharge between electrodesand sealing portions provided on both sides of the light-emittingportion; and a reflector provided behind the light-emitting portion ofthe light-emitting tube and having a reflecting portion that irradiatesthe light beam irradiated by the light-emitting tube after aligning in apredetermined direction, wherein the reflecting portion of the reflectorreflects visible lights and transmits infrared rays and ultraviolet raysin the light beam irradiated by the light-emitting portion of thelight-emitting tube a reflecting portion of the reflector reflectsvisible lights and transmits infrared rays in the light irradiated bythe light-emitting portion of the light-emitting tube attached on thereflecting portion, wherein a plate body having a shape corresponding tothe profile of the reflecting portion of the reflector is providedbehind the reflector with the outer circumference thereof being spacedapart from the reflecting portion of the reflector with a predeterminedgap, the plate body being independent having a shape corresponding to aprofile of the reflecting portion of the reflector and absorbing theinfrared rays and the ultraviolet rays transmitted through thereflecting portion, wherein a cooling channel that passes a coolingfluid is formed between the reflecting portion of the reflector and theplate body, wherein in the sealing portions of the light-emitting tube,the one sealing portion provided on the side near the reflector is fixedon the reflector via a cylindrical heat-conductive member with one endextending behind the reflector, and wherein the plate body is made of aheat-conductive material and is abutted on an end of the heat-conductivemember.
 14. The light source device according to claim 13, furthercomprising: a neck portion provided on the reflecting portion of thereflector to support the sealing portions of the light-emitting portion,wherein the width of the cooling channel formed between the reflectingportion of the reflector and the plate body along an optical axisdirection of the light-emitting portion is minimized at a part near theneck portion of the reflecting portion and enlarged toward a peripheraledge of the reflector.
 15. The light source device according to claim14, wherein the minimum width of the cooling channel is from 5 to 15 mm.16. The light source device according to claim 13, wherein the surfaceof the plate body has irregularities on a side near the reflector.
 17. Aprojector that forms an optical image by modulating a light beamirradiated by a light source in accordance with image information andprojects the optical image in an enlarged manner, the projectorcomprising: the light source device according to claim
 13. 18. Theprojector according to claim 17, further comprising: a neck portionprovided on the reflecting portion of the reflector to support thesealing portions of the light-emitting portion, wherein the width of thecooling channel formed between the reflecting portion of the reflectorand the plate body along an optical axis direction of the light-emittingportion is minimized at a part near the neck portion of the reflectingportion and enlarged toward a peripheral edge of the reflector.
 19. Theprojector according to claim 18, wherein the minimum width of thecooling channel is from 5 to 15 mm.
 20. The projector according to claim17, wherein the surface of the plate body has irregularities on a sidenear the reflector.
 21. A light source device comprising: alight-emitting tube including a light-emitting portion that generateslight by an electric discharge between electrodes; a reflector providedbehind the light-emitting portion of the light-emitting tube and havinga reflecting portion that irradiates the light irradiated by thelight-emitting tube; and a lamp housing that houses the light-emittingtube and the reflector, wherein a reflecting portion of the reflectorreflects visible lights and transmits infrared rays in the lightirradiated by the light-emitting portion of the light-emitting tube isattached on the reflecting portion, wherein a plate body is providedbehind the reflector spaced apart from the reflecting portion of thereflector with a predetermined gap, the plate body having a shapecorresponding to a profile of the reflecting portion of the reflectorand absorbing the infrared rays transmitted through the reflectingportion, wherein the lamp housing has a fixing section that positionsthe reflector in an optical axis direction, wherein the plate body isfixed to the fixing section, wherein a cooling channel that passes acooling fluid is formed between the reflecting portion of the reflectorand the plate body, and wherein the surface emissivity of the surface ofthe plate body is 0.8 or above on a side near the reflector.
 22. Thelight source device according to claim 21, wherein the fixing sectionhas a fixing portion which fixes the plate body, and the plate body isfixed to the fixing portion.
 23. A projector that forms an optical imageby modulating a light irradiated by a light source in accordance withimage information and projects the optical image in an enlarged manner,the projector comprising: the light source device according to claim 21.24. The projector according to claim 23, further comprising: a neckportion provided on the reflecting portion of the reflector to supportsealing portions provided on both sides of the light-emitting portion,wherein a width of the cooling channel formed between the reflectingportion of the reflector and the plate body along the optical axisdirection of the light-emitting portion is smaller at a part near theneck portion of the reflecting portion than at a part near a peripheraledge of the reflector.
 25. The projector according to claim 23, whereina width of the cooling channel formed between the reflecting portion ofthe reflector and the plate body along the optical axis direction of thelight-emitting portion is a minimum at a part near a neck portion of thereflecting portion that supports the light-emitting tube, and a maximumat a peripheral edge of the reflector.
 26. The projector according toclaim 23, wherein a width of the cooling channel formed between thereflecting portion of the reflector and the plate body along the opticalaxis direction of the light-emitting portion is minimized at a part neara neck portion of the reflecting portion that supports thelight-emitting tube and enlarged toward a peripheral edge of thereflector.
 27. The projector according to claim 23, further comprising:an exhaust fan that blows a cooling air along a direction orthogonal tothe optical axis direction to let the cooling air pass through thecooling channel, and an exhaust port from which the cooling air from theexhaust fan is discharged.
 28. The projector according to claim 27,wherein the exhaust fan draws in the cooling air inside the projector.29. The projector according to claim 23, further comprising: a fan thatblows a cooling air along a direction orthogonal to the optical axisdirection to let the cooling air pass through the cooling channel. 30.The projector according to claim 29, wherein the fan draws in thecooling air inside the projector.
 31. The projector according to claim23, wherein the lamp housing is configured in an L-shape formed by thefixing section and a horizontal portion that is fixed to the base of theprojector, and the plate body is fixed to an upper side of the fixingsection that is opposite to an end of the fixing section connected tothe horizontal portion.
 32. The projector according to claim 31, whereina projection is formed on the upper side of the fixing section oppositethe end of the fixing section connected to the horizontal portion, andthe plate body is fixed to the projection.
 33. The projector accordingto claim 23, wherein the reflecting portion of the reflector transmitsultraviolet rays in the light irradiated by the light emitting portionof the light-emitting tube, and wherein the plate body inhibits theultraviolet rays from being transmitted through the reflecting portion.34. The projector according to claim 23, wherein a cover portion isprovided on a front side of the reflector.
 35. The projector accordingto claim 34, wherein the cover portion is formed in an approximatelyconical cylinder.
 36. The projector according to claim 34, wherein thecover portion is attached to an opening of the fixing section of thelamp housing.
 37. The projector according to claim 34, wherein the coverportion is made of a heat absorbing material.
 38. The projectoraccording to claim 34, wherein ultraviolet rays that are radiatedforward of the light-emitting portion are inhibited by the coverportion.
 39. The projector according to claim 34, wherein a fan blowsthe cooling air to the cover portion.
 40. The light source deviceaccording to claim 21, wherein a minimum width of the cooling channel isfrom 5 to 15 mm.
 41. The projector according to claim 23, furthercomprising a neck portion configured on the reflector such that the neckportion supports the light-emitting tube, wherein a width of the coolingchannel between a part near the neck portion and the plate body alongthe optical axis direction of the light-emitting portion is from 5 to 15mm.
 42. The projector according to claim 23, further comprising sealingportions provided on the light-emitting tube, wherein one sealingportion provided on a side near the reflector is fixed to the reflectorvia a cylindrical heat-conductive member with one end of the sealingportion extending behind the reflector, and wherein the plate body ismade of a heat-conductive material and is abutted on an end of theheat-conductive member.
 43. The light source device according to claim21, wherein the fixing section consists of a vertical portion.
 44. Aprojector comprising: a light-emitting tube including a light-emittingportion that generates light by an electric discharge between electrodesand sealing portions provided on both sides of the light-emittingportion; a reflector provided behind the light-emitting portion of thelight-emitting tube and having a reflecting portion that irradiates thelight irradiated by the light-emitting tube after aligning in apredetermined direction; and a lamp housing that houses thelight-emitting tube and the reflector, wherein a reflecting portion ofthe reflector reflects visible lights and transmits infrared rays in thelight irradiated by the light-emitting portion of the light-emittingtube, the light-emitting tube being attached on the reflecting portion,wherein a plate body is provided behind the reflector spaced apart fromthe reflecting portion of the reflector with a predetermined gap, theplate body having a shape corresponding to a profile of the reflectingportion of the reflector and absorbing the infrared rays transmittedthrough the reflecting portion, wherein the lamp housing has a fixingsection that positions the reflector in an optical axis direction,wherein the plate body is fixed to the fixing section, wherein a fanblows a cooling air between the reflecting portion of the reflector andthe plate body, and wherein the surface emissivity of the surface of theplate body is 0.8 or above on a side near the reflector.
 45. A projectorcomprising: a light-emitting tube including a light-emitting portionthat generates light by an electric discharge between electrodes andsealing portions provided on both sides of the light-emitting portion; areflector provided behind the light-emitting portion of thelight-emitting tube and having a reflecting portion that irradiates thelight irradiated by the light-emitting tube after aligning in apredetermined direction; and a lamp housing that houses thelight-emitting tube and the reflector, wherein a reflecting portion ofthe reflector reflects visible lights and transmits infrared rays in thelight irradiated by the light-emitting portion of the light-emittingtube, the light-emitting tube being attached on the reflecting portion,wherein a plate body is provided behind the reflector spaced apart fromthe reflecting portion of the reflector with a predetermined gap, theplate body having a shape corresponding to a profile of the reflectingportion of the reflector and absorbing the infrared rays transmittedthrough the reflecting portion, wherein the lamp housing has a fixingsection that positions the reflector in an optical axis direction,wherein the plate body is fixed to the fixing section, wherein a fanblows a cooling air between the reflecting portion of the reflector andthe plate body, and wherein the minimum width of the cooling channel isfrom 5 to 15 mm.
 46. The projector according to claim 44, wherein thefixing section consists of a vertical portion.
 47. A projectorcomprising: a light-emitting tube including a light-emitting portionthat generates light by an electric discharge between electrodes andsealing portions provided on both sides of the light-emitting portion;and a reflector provided behind the light-emitting portion of thelight-emitting tube and having a reflecting portion that irradiates thelight irradiated by the light-emitting tube after aligning in apredetermined direction, wherein a reflecting portion of the reflectorreflects visible lights and transmits infrared rays in the lightirradiated by the light-emitting portion of the light-emitting tubeattached on the reflecting portion, wherein a plate body is providedbehind the reflector spaced apart from the reflecting portion of thereflector with a predetermined gap, the plate body having a shapecorresponding to a profile of the reflecting portion of the reflectorand absorbing the infrared rays transmitted through the reflectingportion, wherein a cooling channel that passes a cooling fluid is formedbetween the reflecting portion of the reflector and the plate body, andwherein the minimum width of the cooling channel is from 5 to 15 mm. 48.A projector comprising: a light-emitting tube including a light-emittingportion that generates light by an electric discharge betweenelectrodes; a reflector provided behind the light-emitting portion ofthe light-emitting tube and having a reflecting portion that irradiatesthe light irradiated by the light-emitting tube; and a lamp housing thathouses the light-emitting tube and the reflector, wherein a reflectingportion of the reflector reflects visible lights and transmits infraredrays in the light irradiated by the light-emitting portion of thelight-emitting tube attached on the reflecting portion, wherein a platebody is provided behind the reflector spaced apart from the reflectingportion of the reflector with a predetermined gap, the plate body havinga shape corresponding to a profile of the reflecting portion of thereflector and absorbing the infrared rays transmitted through thereflecting portion, wherein the lamp housing has a fixing section thatpositions the reflector in an optical axis direction, wherein the platebody is fixed to the fixing section, wherein a cooling channel thatpasses a cooling fluid is formed between the reflecting portion of thereflector and the plate body, and wherein the minimum width of thecooling channel is from 5 to 15 mm.